Hello, I have looked around forums and haven’t seemed to catch anything about how to implement an articulated Robotic Arm with Ardusub.Not just a grippier.
Before ordering the whole Pixhwk/ardusub system, I am trying to understand and figure out what it would be the most covnenient way to pair a 5 or 6 axis arm on my ROV project.
If ardusub is preconfigured for this, where do I plug the servowires onto (the navigator?).
Do I need to make my own code or I can use ardusub, if yes, at which conditions?
Thanks support in advance
Hi @kostantin, welcome to the forum 
This sounds like an interesting project! 
ArduSub does not currently have any articulation motor controls built in, and does not contain any inverse kinematics or input commands for a robot arm. The existing gripper support is handled as a single servo-style motor output, which is only used for opening/closing the end effector jaws.
Accordingly, you’ll need to write your own code. This could be implemented as an addition to the ArduPilot codebase (which ArduSub uses a subset of), or the manipulator could have its own control electronics and just use ArduSub (or BlueOS) to send the abstract commands to the arm (e.g. via I2C).
The only multi-axis robot arm I’m aware of for underwater vehicles at this size range is the Reach Alpha.
The Navigator and Pixhawk are both flight controller boards - they do similar things, and are not expected to be used together in the same vehicle.
If you choose to implement your arm control within ArduSub, it’s worth noting that the Navigator has 16 PWM outputs (which include those for the thruster outputs) compared to the Pixhawk’s 14 (which include the thruster outputs, and generally have one assigned to be used as a leak sensor). ArduSub-based ROVs most commonly have 6 or 8 thrusters, and I expect the additional stability and motion axes from 8 thrusters organised like in our BlueROV2 heavy configuration would be recommended for a use-case that involves a robot arm.
Hey, thanks for your answers. It’s not easy to plan such an arm without having in my hands the necessary hardware. And I wouldn’t end up making a purchase to realize that it was not a viable option. So let me say it with my own words, to make sure that I begin to understand the best course of action.
The “Navigator” would allow me to plug 5 or even 6 servos, to send signal and “Dedicated” power to the ARM ( that by the way it would need about 8V minimum). That being said, I should program (in C#Script hopefully) the necessary code for each of the 6 servos following the logic of Potentiometer VS analog gamepad: The actual movement of the servos should be triggered by the available buttons of a generic Gamepad. I might need a verbal conversation to clear all my questions. If any kindred spirit is willing to reach such a generosity, please let me know. There is teams,skypeor whatever, considering that I live somewhere in The United Arab Emirates (zulu+4). Best regards and thanks again